This is a long term, multicenter trial using the MiniMed Implantable Pump (MIP) for the treatment of type 1 diabetes. The pump itself derives from that developed first at the Johns Hopkins University Applied Physics Laboratory, where Dr. Saudek collaborated, providing the clinical in-put in design decisions. Pre-clinical trials were then done at Johns Hopkins Hospital of the original PIMS device, prior to first human implantations. In 1990, the initial MIPs were fabricated by MiniMed, as the next generation PIMS. Since then, Dr. Saudek has been the lead investigator in the U.S., with major input into the protocol, first use of such approaches as the catheter flush, and publishing results along the way. He was chairman of the independent V.A. Cooperative Study of Implantable Insulin Pumps, published in 1996. In the period of about 1996-1998, there was a significant problem when the insulin formulation used was changed, and the new insulin had a greatly increased incidence of aggregatin within the pump. The project currently is designed to continue to test the efficacy and reliability of the system, with its new insulin formulation. A re-design of the pump will be forthcoming.